/*
 * Copyright (C) 2016 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.graph;

import com.google.common.annotations.Beta;

import javax.annotation.CheckForNull;

/**
 * This class provides a skeletal implementation of {@link Graph}. It is recommended to extend this
 * class rather than implement {@link Graph} directly.
 *
 * @param <N> Node parameter type
 * @author James Sexton
 * @since 20.0
 */
@Beta
@ElementTypesAreNonnullByDefault
public abstract class AbstractGraph<N> extends AbstractBaseGraph<N> implements Graph<N>
{

    @Override
    public final boolean equals(@CheckForNull Object obj)
    {
        if (obj == this)
        {
            return true;
        }
        if (!(obj instanceof Graph))
        {
            return false;
        }
        Graph<?> other = (Graph<?>) obj;

        return isDirected() == other.isDirected()
                && nodes().equals(other.nodes())
                && edges().equals(other.edges());
    }

    @Override
    public final int hashCode()
    {
        return edges().hashCode();
    }

    /**
     * Returns a string representation of this graph.
     */
    @Override
    public String toString()
    {
        return "isDirected: "
                + isDirected()
                + ", allowsSelfLoops: "
                + allowsSelfLoops()
                + ", nodes: "
                + nodes()
                + ", edges: "
                + edges();
    }
}
